Optical instruments refer to devices that utilize optics and light to capture and manipulate images or signals for various purposes. These instruments include telescopes, microscopes, cameras, spectrometers, and lasers. They play a crucial role in a wide range of fields such as astronomy, biology, medicine, and materials science. Optical instruments work by focusing and manipulating light to provide magnified images or precise measurements of objects, allowing researchers to study and understand the physical properties and interactions of different materials and structures.